Background The aim of this magnetic resonance imaging (MRI) study was to investigate controversial sexual dimorphism of the posterior condylar ofset of the femur (the ofset) and the posterior slope of the tibia (the slope) in non-arthritic knees of Egyptian adults. Methods On 100 male and 100 female MRIs of non-arthritic knees, linear measurements of the distal part of the femur (the ofset) and the angular measurements of the proximal part of the tibia (the slope) were performed and compared regarding sex and ethnicity. The intraclass correlation coefcient (ICC) was used to test the interrater agreement. Results Both ofsets and the lateral ofset ratio were larger in males (p0.8 proved MRI’s precision was high. Conclusion There was a sexual dimorphism of both the ofset and the medial slope in non-arthritic knees of Egyptian adults. We believe future designs of knee implants should consider these diferences in order to improve postoperative range of motion and patients’ satisfaction after total knee arthroplasty. Level of evidence Level III Retrospective Cohort Study. Trial registration ClinicalTrials.gov identifer: NCT03622034, registered on July 28, 2018.